A marker recognition unit recognizes a marker printed on a plane or a cubic plane and acquires corresponding data of the marker. Such marker recognition unit has been applied to a learning system, called electronic learning (e-learning) or ubiquitous learning (u-learning), in combination with augmented reality technology.
The virtual reality is conceptually opposite to the augmented reality. The virtual reality is one of new paradigms of an information activity field. The virtual reality is designed to make a user indirectly experience situations that the user cannot experience in the real world due to spatial and physical restrictions through an interaction with a human sensory system in a virtual space built up by a computer. An ultimate goal of the virtual reality is to provide an environment that allows a user to communicate with a computer more realistically by improving the capability of communicating with a computer using various input/output devices. As the input/output devices for a user and a computer, a head-mounted display (HMD), a data glove, and a motion capture device have been used. The HMD transmits position data that changes according to the head movement of a user to a computer. The computer simulates an object to be shown to a user by calculating the size and depth of an object based on the received position data. The data glove senses positions and moving directions of hands of the user. When the user moves his hands in a three-dimensional space, the data glove transmits corresponding data to the computer in three-dimensional coordinates. The computer manipulates an object based on the received data.
The augmented reality is a term derived from a virtual environment and the virtual reality. The augmented reality denotes mixing a real-world image with a virtual image by inserting a computer graphic image in a real-world environment.
Real-world information may include unnecessary information or may not include sufficient information that a user needs. It is possible to simplify the unnecessary information or to make the unnecessary information not to be shown by using a computer-simulated virtual environment. In other words, an augmented reality system enables interaction with a user in real time by combining a real world with a virtual world.
Simple examples of the augmented reality appear in weather forecast and entertainment areas. When a weather forecast is presented on TV, viewers watch a weather map behind a weatherman change smoothly. What is actually happening, however, is that the weatherman is standing in front of a blue screen and a computer simulates virtual images in a virtual studio environment, which is the augmented reality. Further, the augmented reality may be applied to a medial area and help a doctor smoothly carry out an operation on a patient by acquiring three-dimensional data of the patient in real time through indirect tests, such as magnetic resonance images (MRI), computed Tomography Image (CTI), and ultrasonic images, rendering the acquired data in real time, and representing them overlapped with the patient. Also, the augmented reality may be applied to aviation and provide a pilot with much information needed for flight by displaying virtual image on a visor of the pilot's helmet or the windshield of the flight deck.
There is a conventional marker recognition system that recognizes a three-dimensional marker in a real image using a Descartes coordinate type three-dimensional marker. Further, there is another conventional technology for improving the performance of extracting a marker ID. In this conventional technology, a marker is divided into 36 regions. Then, 10-bits of the marker are used to identify a marker ID, and 26-bits of the marker are allocated as a cyclic redundancy check (CRC) code in order to improve the performance of extracting the marker ID.
There are several problems in realizing a ubiquitous learning system by combining the above-described conventional marker recognition technology with the augmented reality technology.
A marker recognition technology is required to be robust in various camera and illumination environments. Also, since learners tend to be uncomfortable with a marker printed on a learning material of a ubiquitous learning system, the size of the marker printed on the learning material is made as small as possible while increasing the recognition rate of the marker. Furthermore, as the number of pages of a book increases, the kinds of markers included in a book become diverse. Therefore, it is required to develop a pattern authoring and recognizing mechanism that can efficiently author and recognize the diverse kinds of markers.